Provide each student with the following set-up:
A paper towel with a piece of wax paper on top of the towel. A small cup of water and a pipette next to the wax paper.
Begin by showing students the pipette, naming the bulb and stem.
Walk students through the process of using a pipette:
--Squeeze the bulb
--Place the stem in the water
--Release the bulb
--Remove the stem from the water
--Squeeze the bulb a small amount to release a drop of water.
Guide the students through the following exercises:
--Make a single drop on the wax paper.
--Use the pipette to pick up the drop of water.
--Move the drop of water around the piece of wax paper.
--Make 2 or 3 drops of water on the wax paper and push the drops together.
--Split the drop of water into smaller drops.
--Make a picture using drops of water (a face, for example).
Without even trying, the students will learn a lot about the nature of water by observing the shape of the drops, watching the drops come together, and struggling to separate the drop into smaller drops.
With older students, you'll discuss adhesion, cohesion and surface tension, maybe even mentioning Hydrogen bonds.
With younger students you'll discuss what you saw happening and the general idea that the water likes to stick to itself.
If your students are on a roll with this activity, here are a few extentions you can use:
- Have the students make drops of oil and/or rubbing alcohol on the wax paper. Guide them through the same exercises and above and see if these liquids behave in the same manner as water.
- Have students make their drops of water on other materials: paper towels, aluminum foil, plastic wrap. How does the water behave on each of the surfaces?
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Activity from Linda Burroughs, The College of New Jersey, presented at the 2010 New Jersey Science Teachers Association Convention
